In one game of the 1978 world championship, Karpov now played the extraordinary 11. Ng5]? against Korchnoi. Later analysis showed that 11 . . . Qxg5 12. Qf3 0-0-0] 13. Bxe6+ fxe6 14. Qxc6 Qxe5 is not bad for Black.

By most normal standards, this position should favour White: rook and bishop generally co-operate better than rook and knight; bishops are superior to knights when there are rival pawn majorities on opposite sides of the board, and here White has good prospects of driving Black back with a quick f5. Anand, however, has spotted that White's bishop is not as good at it looks.

24. f4 f5]

The routine 24 . . . g6? would leave White on top after 25. g4.

25. exf6+ Kxf6 26. f5

White might delay this with 26. Be3, but Kf5 is an irritating reply. 26. c4]? is another idea, but the move played is most natural.

26 . . . Nc5 27. Be3 Ne4 28. Bd4+ Kf7 29. Be5

Well behind on time (like most of Anand's opponents), Adams decides to simplify - but it turns out not to be simple at all. Instead 29. Ra1 Re8 30. Ra7 Re7 would preserve a dynamic equilibrium.